Kisu Meguru Sekai

A fourteen-year-old girl harbors a deep affection for her teacher, yet she lacks the courage to confess her feelings. However, an accidental kiss shatters her ordinary life, instantly transporting her into a parallel world where her beloved teacher exists as a scientist. There, she uncovers a startling truth: he is actually an alien observer. She soon realizes that every time their lips meet, she is thrust into yet another alternate reality, each featuring a slightly different version of him. Despite these constant shifts in circumstance and identity, one thing remains unwavering—her heart still belongs to him in every single universe she visits. Understanding the unpredictable nature of her situation, the teacher provides her with a specialized device designed to ensure her safety across dimensions. This tool allows a version of him within each new world to locate and protect her whenever she arrives. Armed with this lifeline, she must navigate an endless chain of parallel realities, relying on his various incarnations for guidance and rescue while searching for a way to finally return to her original world.